1. Field of the Invention
Aspects of the present invention relate to a battery management system (BMS). More particularly, aspects of the present invention relate to a BMS that can be used in a vehicle using electrical energy, and a driving method thereof.
2. Description of the Related Art
Vehicles that use internal combustion engines fueled by gasoline or heavy oil have caused serious air pollution. Accordingly, companies have made various efforts to develop electric and hybrid vehicles to reduce air pollution.
An electric vehicle uses a battery motor operating by electrical energy output from a battery. Since the electric vehicle is primarily driven by the battery, which is formed out of one battery pack including a plurality of rechargeable and dischargeable secondary cells, there is merit in that the electric vehicle does not emit emission gases and makes less noise.
The term “hybrid vehicle” commonly refers to a gasoline-electric hybrid vehicle that uses gasoline to power an internal-combustion engine and an electric battery to power an electric motor. Recently, companies have developed various types of hybrid vehicles, such as hybrid vehicles using an internal-combustion engine and fuel cells, and hybrid vehicles using a battery and fuel cells. The fuel cells directly obtain electrical energy by generating a chemical reaction while hydrogen and oxygen are continuously provided.
A vehicle driven by an electric motor uses secondary cells to power the vehicle, and since the secondary cells directly affect the performance of the vehicle using electrical energy, each secondary cell should have great performance. Also, a battery management system (BMS) should be provided in these hybrid vehicles to measure a voltage and a current of the overall battery to efficiently manage charging and discharging operations of each battery cell.
To manage the battery, the BMS should measure an internal resistance of the battery. However, when calculating the internal resistance of the battery by using an external resistor connected to a terminal of the battery, the external resistor may cause a power loss. Therefore, it is desirable to reduce power loss caused by the external resistor when the battery and the external resistor are coupled to calculate the internal resistance of the battery.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.